Marda Ro (seen in the image), made mention of the Rad within the pages of her personal journal.
The Rad were a collective of Evereni, and their designation translated to "to laugh" when spoken in their species' native tongue. The siblings Vika and Velya Faer, both Evereni, were knowledgeable regarding the Rad, and in fact, knew Evereni who bore the name. At a time occurring no earlier than 379 BBY, the Faer pair encountered Marda Ro, an Evereni individual who initiated a pirate organization that would eventually evolve into the group known as the Nihil. Ro, in an effort to expand her understanding of the Evereni, requested that they enlighten her on the subject. Vika and Velya complied, sharing information about the Rad, among other topics.
At a later point, Ro created a recorded message intended for her progeny, in which she referenced the Rad as a piece of information she had acquired from the Faers. By the year 252 BBY, during his formative years, Marchion Ro, her great-great-grandson, had listened to her journal, including the segment where the Rad received a mention.
The Rad were first brought up in the short story titled "A Closed Fist Has No Claws," penned by Tessa Gratton and featured in the 2023 young-adult collection titled The High Republic: Tales of Light and Life, which itself is a part of the larger Star Wars: The High Republic multimedia project. In an interview, Gratton stated that the Evereni naming system was among the first elements she conceived. Gratton's reason for establishing this naming system was born from a dissatisfaction with the lack of such conventions within the Star Wars universe.